Fuel burning air heating apparatus



April 23, 1957 R. R. DUPLER 2,789,554

FUEL BURNING AIR HEATING APPARATUS Filed April 1, 1955 2 Sheets-Sheet 1 40 mi Fm E E O F .34 1 35 23 i 0 8g m 33 V37 1 it; f: OQ I -5 L28 I la 23 '/5 I 2 -Cf' r 32 39 00mm A a B THERMOSTAW F Q3 L P 43 l4 27 F J 5 COMBUSTION \p b ,7 CHAMBER INVENTOR. Ray/7M0 f3 flap/9r 25 26 BY q I 24 /5 ATTORNEY A M M *,444 MM April 23, 1957 Filed April l, 1955 R. R. DUPLER FUEL BURNING AIR HEATING APPARATUS 2 Sheets-Sheet 2 INVENTOR. Raymond A. Dup/er WAMMAAQQ ATTORNE Y U d States Patent 2,789,554 FUEL BURNING AIR HEATING APPARATUS Raymond R. Duplex-,- Toledo, Ohio Application April 1, 1955, SerialNo. 498,512

7 Claims. (Cl. 126-63) This invention relates to heating apparatus but more particularly to that type of apparatus employing products of combustion as the source of heat, and an object is to produce a new and improved heater of the above character for heating fluids such for example as, air and the like.

Another object is to improve the efficiency of heaters of the above type and to produce a relatively inexpensive unit having the unique features of construction and arrangement hereinafter described.

Other objects and advantages will. hereinafter appear and, for purposes of illustration but not of limitation, an embodiment of the invention is shown on the accompanying drawings in which Figure l is a front elevation of a heating apparatus embodying the invention;

Figure 2 is a vertically sectional elevation substantially on the line 2--2 of Figure 1;

Figure 3 is an enlarged fragmentary sectional view substantially on the line 33 of Figure. 2;.

Figure 4 is a view substantially on the line 44 of Figure 3; and

Figure 5 is a fragmentary sectional view showing particularly the bypass from thecombustion. chamber to the collecting header and a damper controlling such by-pass.

The illustrated embodiment of the inventioncomprises a housing resembling a fireplace designated by the reference letter H, the same being employed for heating the air within a room. The housing'is formed with a vertical front wall having a window opening 11 in the lower portion thereof, the same being covered by a door or frame 12, which preferably can be removed or swung outwardly to afford access. to the interior. Suitably carried by the door or frame 12 in an inner glass panel 13 and an outer glass panel 14 separated slightly from each other, uch panels enabling the occupant of the room to view the burner unit B, which is disposed within a combustion chamber C. The burner unit B may be made to burn gas or oil for example and have an exposed flame, which as above mentioned may be viewed from the outside of the. housing.

The combustion chamberC has a front wall 15.having an opening registering with the opening 11 of the housing. The housing H has a bottom wall 16 and a rear wall 17, which extends upward vertically and then gradually curves upwardly and inwardly, as indicated at 18,' and then terminates in a. vertical upper portion 19 which is in parallel relationship to the front wall ll) of the housing. A top wall 20 connects the top edgesof the front and the rear walls of the. housing. and at the. ends of the housing are upright end walls. 21 which are, secured'to the front and rear Walls thereby forming. an -enclosure; The:housing is formed fromv sheet metal. of'the; desired gauge. and, as shown, there is. an elongate rectangular: opening 23 at the upper. portion of the front. wall 10 which constitutes an hotair outlet. Thisjopen'ingis' coveregtby; a screen or toraminous. sheet 23.. .lntthebott m-portion ofgthe front wall 10 is. an elongate opening; 24 substantially smaller than the opening 23, the same being covered by a screen 25 and this opening serves as an inlet for cold air from the room.

Connected to the front. wall 15. of the combustion chamber C is a bottom wall 26v which is spaced upwardly from the bottom wall 16' of'the housing H. Secured to the rear end of the bottom wall 26 is a rear Wall 27, which is spaced inwardly from. the rear wall 17 of the housing and curves upwardly and inwardly similar to the wall 17. At the top of the combustion chamber is a top wall 28 connecting the front and rear walls of the combustion chamber. Manifestly at opposite ends are end walls 28a closing the opposite sides or ends of the corn: bustion chamber.

Formed in the extreme front portion of the top wall 28 of the, combustion chamber and. extending completely across such Wallis a rowof equidistantly spaced holes. In this instance there are twelve holes and for assistance in describing the structure, these holes will be referred to in. groups, the end. groups 29 and. 30 of four each being disposed at the outer sides or ends of the row and a group 31 being disposed in the center, the latter also containing four holes. Extending upwardly at substantially right angles from the top wall'28 and connected to the holes in. the groups 29 and 30. are Lfshaped tubes 32, the inner ends of which connectto the opposite side walls. of the front compartment or chamber. of a collecting header 33. As shown particularly in Figure 3, the tubes 32 are arranged in somewhat nested form, those toward the center having the shorter vertical and horizontal arms and being connected to the lowermost portion of the side walls of the header. Then. theother two are spaced equidistantly from each other and progressively become of greater length having a. longer vertical and horizontal arm. Thus the connection to the header forms vertical rows on opposite sides at the front end of the collecting header, particularly as shown in Figure 2. The right angle bend of the tubes 32 is for the-purpose of restricting the flow of the products of combustion passing therethrough to enable as much of that heat as possible. to be utilized.

It will be noted that the collecting header 33 is in the form of a sheet metal rectangular box, the front end of which is open. A plate 34 closes the front end and this plate is connected by removable fasteners 35 to a flange formed at the front end of' the header. This enables access to the interior of the box to behad by removing the closure plate 34, it being understood that the screen 23 must first be removed in order to obtain access to the closure plate 34:.

Extending from the group of holes 31 at the center and forming the central group of openings are curved return bend tubes 36. It should be. noted that each of the tubes 36 are curved throughout at all bends and do not have the right angle bends as formed in the tubes 32. For example, the extreme end tubes 36 or those tubes closest to the L-shaped tubes 32 curve upwardly from theopenings 31 and thus extend horizontally substantially parallel with the top wall 28 of the combustion. chamher and outwardly beyond the side walls. 28a of thecombustion chamber to a point close to theend walls 21 ofthe housing H. Thence. thesetubes extend rearwardlyto a point about in line with the inner. end of the collecting headerv 33 and thence. incline forwardly and upwardlyto. the bottom wall of the header 33' adjacent the front end thereof; The/two intermediate tubes 36 likewisecurveupwardly from their openings 31 and thence laterally and rearwardlyto the rear wall portion. 19 of the housing; and thence. curve. forwardly and inwardly terminating in upwardly-curved ends" connected to the front portion: of: the bottom wall of the header33; Thus the endsofithecnrved tubes 36' are arranged in a row' 3 at the front portion of the bottom wall of the header, particularly as indicated on Figure 4.

The interior of the collecting header 33 is divided into two chambers, a front and rear chamber, by a vertical bat-fie plate 37, which is removably connected to a flange 39 by fasteners 38. Thus by removing the front closure plate 34 access can be had to the bafiie plate 37 which can also be removed to enable the tubes to be cleaned, as will more fully appear hereinafter.

The front and rear chambers of the collecting header are connected by relatively long hair-pin shape tubes 40, there being four relatively long hair-pin tubes 40. The front ends of the tubes 40 connect to the side walls of the header and then extend outwardly in a horizontal direction and terminate in curved portions adjacent the side walls 21 of the housing. Then the tubes extend inwardly in a horizontal fashion and parallel to the other arm of the U and connect to the same side wall of the header but at a point close to the rear wall of the header, as shown on Figure 4. Thus there are four hair-pin like tubes 40 in each side of the header and they connect to openings arranged in a row parallel to the connecting openings between the L-shaped tubes 32 and the side wall of the header, all as indicated in Figure 2. Disposed intennediately of the relatively long hair-pin tubes 40 are relatively short hair-pin tubes 41, there being three of such tubes on each side of the header. These do not extend out quite so far as the relatively long tubes but terminate adjacent the side walls 28a of the combustion chamber, as indicated in Figures 3 and 4, and the opposite ends connect to openings arranged in the header on the inner side of the bafile plate 37 adjacent thereto, these also being arranged in a row and being disposed forwardly of the rear connecting openings of the relatively long tubes 40, as shown in Figure 2.

Integral with the collecting header and disposed at its rear wall thereof is a relatively short smokepipe 42, which extends through an opening in the rear wall portion 19 of the housing H, this providing a conduit to which suitable connection can be made to the smoke chimney, as will be readily understood.

It is desired that when the burner B is first turnedfon and before heat has been generated to any extent, that the products of combustion pass directly to the rear compartment of the collecting header 33. For this purpose a bypass pipe 43 extends vertically from the top wall 28 of the combustion chamber C to the bottom wall of the header at a point in rear of the baffle plate 37. Disposed within the bypass pipe 43 is a pivotly mounted damper 44 rotated by a horizontally disposed shaft, which extends forwardly towards the front of the housing H. A suitable thermostat 46 is provided in the region of the screen 23, a so-called spiral thermostat being found to be satisfactory for this purpose, the same operating to turn the shaft 45 when a predetermined degree of temperature has been reached thereby to close the damper 44 and cause the product of combustion to pass through the tubes above described. The damper will then stay closed so long as the proper heat is generated but when the burner B is shut oif or automatically goes oif, then the thermostat 46 operates automatically to open the damper 44 and hold it in opened position until heat of predetermined degree has again been generated. Thermostats of this character are well known in the art and detail description and illustration thereof are not considered necessary.

From the above it will be understood that I have produced a highly efficient and economical heater from which the maximum heat is extracted from the products of combustion issuing from the combustion chamber C. The arrangement of 'the curved return bend tubes 36 is important because they are connected to the combustion chamber where the heat is the greatest. The gases are permitted to pass through these tubes with as littlerestriction of movement as possible, this being the speed of their passage is intentionally restricted by the right angle construction of these tubes. The gases which enter the front chamber of the collecting header have a large portion of the heat extracted but most of the heat which remains is dissipated in passing through the hairpin tubes 40 and 41 to the rear chamber of the collecting header where they pass from the apparatus through the smokepipe 42. Thus the gases which enter the smokepipe 42 are relatively cool, as cool as can reasonably be permitted.

As shown the cold air enters the heating apparatus through the inlet 24 at the base of the housing H and then passes upwardly through the space between the rear wall of the combustion chamber and the rear wall of the housing and in this passage the air is preheated since the rear wall of the combustion chamber is heated. Then the air passes over and about the network of tubes above described so that as discharged into the room through the screened outlet 22, the air will be substantially heated.

The feature by which the tubes can be readily cleaned is of importance. To accomplish this the screen 23 is first removed to enable access to be had to the closure plate 34 which-can then be easily unfastened. Thereafter the baffle 37 can be removed to gain access to the inner ends of the hairpin tubes 40 and 41. The combustion chamber door or frame 12 can be removed or opened for access to the opposite ends of the tubes 32 and 36.

As above pointed out, the gases from the combustion chamber C pass directly to the outside through the bypass pipe 43 until such time as sufiicient heat is generated by the burner C whereupon the damper 44 is automatically closed by the thermostat 46 and remains closed so long as a predetermined heat is being generated in the combustion chamber. However, when the burner B is turned ofi or fails to generate the proper heat, then the damper 44 is automatically opened and held in open position until the proper heat is again generated.

Numerous changes and details of construction, arrangement and choice of materials may be effected without departing from the spirit of the invention especially as defined in the appended claims.

What I claim is:

1. Heating apparatus comprising a shell forming a combustion chamber adapted to receive a heater therein, a housing enclosing said shell and spaced therefrom at the sides and rear to provide a passage for air to be heated, said shell and housing being provided with means forming a common framed opening at the front, means forming an inlet for air to the lower portion of the passage, a collecting header in spaced relation to the top of the combustion chamber shell and housing walls to receive products of combustion from said combustion chamber, a bafiie separating the interior of the header into front and rear compartments, a series of tubes leading from the combustion chamber to the front compart ment and arranged in the path of movement of air from said inlet means, tubes connecting said front and rear compartments and extending from the collecting header in the path of movement of air from said inlet means, means forming an outlet for heated air in front of the header and tubes, and means providing a conduit from the rear compartment to the outside of the housing forming an outlet for the products of combustion.

2. The organization as claimed in claim 1 in which the series of tubes from the combustion chamber to the collecting header comprises U tubes extending from the central top of the combustion chamber, and L-shaped tubes communicating with the combustion chamber on laterally opposite sides of the central top of the combustion chamber.

3. The organization as claimed in claim 2 in which the tube means connecting the front and rear header compartments are hairpin shaped.

4. The organization as claimed in claim 3 in which the hairpin shaped tubes comprise a vertical row of relatively long tubes and a vertical row of tubes substantially shorter than said long tubes.

5. The organization as claimed in claim 1 in which the collecting header comprises a box open at the front, a removable plate closing said front, and a mounting for the baffle enabling removal thereof to effect cleaning of the tubes.

6. The organization as claimed in claim 1 comprising a by-pass pipe extending directly from the combustion chamber to the rear compartment, a damper in said pipe,

6 and thermostatic means responsive to rise in temperature of the air heated by the heater to close the damper for actuating said damper.

7. The organization as claimed in claim 1 comprising a glass panel covering the framed opening in the housing and shell affording a view of the burner within the combustion chamber and access to the tubes leading therefrom for enabling cleaning thereof.

References Cited in the file of this patent UNITED STATES PATENTS 165,259 Ruttan July 6, 1875 512,689 Eskil Jan. 16, 1894 2,172,667 Nelson Sept. 12, 1939 2,429,748 Dollinger Oct. 28, 1947 2,671,440 Dupler Mar. 9, 1954 

